The invention concerns a forming element for an absorbent article, such as a sanitary napkin, an incontinence protector or a panty shield, which forming element is formed of a rigid material and exhibits a principally elongate form with a longitudinal direction and a transverse direction, an upper side, an underside, two short sides and two long sides, a first and a second end portion and an intermediate portion.
The invention further concerns an absorbent article, such as a sanitary napkin, an incontinence protector or a panty shield, which article has a principally elongate form with two end portions and an intermediate portion situated between the end portions.
Absorbent articles, such as sanitary napkins, incontinence protectors and panty shields are subjected during use to great forces, for example when the user is walking. The absorbent article is then sheared between the thighs of the user. A conventional absorbent article is usually manufactured in soft materials, which wrinkle under the effect of these forces. Wrinkles result in a reduction of the reception area on the article for liquid which is emitted from the user. Moreover, the wrinkles form channels in which liquid on the surface of the article can run out towards and over the edges of the article. In other words, there is an increased risk of leakage.
This problem has been solved by providing the article with forming elements of shape stable material which can withstand stresses during use. Such articles are described in, for example, PCT/SE97/01881, PCT/SE97/01882 PCT/SE97/01885 and PCT/SE97/01886.
Furthermore, it is not unusual for the attachment system of the absorbent article to lead to leakage problems. Usually, absorbent articles, such as sanitary napkins, are attached in the underclothes of the user using glue. As a result, the article follows the movements of the underclothes rather than the body movements of the user. Displacements and gaps between the body of the user and the article can lead to the available reception area becoming insufficient. Moreover, liquid can leak out between the article and the body of the user.
This problem, also, is solved in the above publications by means of the physical design of the forming element in combination with the rigidity of the forming element. By forming an article in such a way that it conforms to a high degree with the body shape of the user and by ensuring that its rigidity is sufficiently high to avoid deformation, an article can remain in place during use without the need for special attachment devices. Such an article will follow the body movements of the user during use, thus considerably reducing the risk of leakage.
In order for an article to fit well and to stay in place against the body, it should not be flat, inasmuch as the anatomical parts the article is to fit against are not flat. One alternative is to give the forming element a three-dimensional form. Another way to solve the problem is to design a principally flat forming element in a principally flat article, which, due to the design of the article, becomes three-dimensional during use. An article of that kind is described in the Swedish patent application SE702463-2. Other ways to achieve forming during use are to provide the article with folding indications, or the like.
In order to function as intended and to make the absorbent article shape stable, the forming element must be made of a rigid material and exhibit a sufficient thickness. If the forming element has a high thickness the total weight of the absorbent article will also be high. A high weight of the absorbent article can lead to problems, for instance concerning transport and user comfort.
A purpose of the present invention is therefore to obtain a forming element with low weight but necessary rigidity and an absorbent article containing such a forming element.
An article of the type mentioned in the introduction, with which the problems associated with previously known articles of this type have been essentially removed, is characterised, according to the invention, in that the forming element exhibits one or several corrugations.
The article preferably exhibits a ridge-like raised portion arranged on the upper side of the forming element in the longitudinal direction of the forming element in the second end portion.
The invention can be further characterised in that the corrugations are arranged in the first end portion, in the second end portion, which is intended to face backwards on the user during use, or in both end portions.
According to an alternative embodiment of the invention, the corrugations are arranged as elongate raised portions or depressions on the upper side of the forming element and exhibit a longitudinal direction and a transverse direction, wherein the corrugations are arranged with their longitudinal direction principally in the transverse direction of the forming element.
The forming element according to the invention can be further characterised in that the widest part on the first end portion is 1.5-5 times as wide as the narrowest width on the intermediate portion.
The invention also concerns an absorbent article comprising a forming element in accordance with what is stated above.
The above-mentioned problems are solved by means of the present invention. This is achieved by manufacturing the forming element of a relatively thin material layer and by arranging corrugations in the forming element.
A forming element according to the above-mentioned PCT/SE97/01881 is manufactured of a rigid layer, for example a plastic layer. Polystyrene or mineral-filled polypropylene with a layer thickness of at least 0.4 mm can be mentioned as examples of plastic materials which are stated as having sufficient rigidity and torsion rigidity to reach the necessary shape stability.
The shape stability of a forming element of the kind intended here must be sufficiently great to essentially enable the article to retain a predetermined and predictable form during use. Thus, it is possible to form the article in such a way that it lies in place against the body of the user during use without the need for special attachment members such as attaching glue or the like. The material stiffness of the layer material that is used in the forming element is of course significant to the shape stability of the forming element. Plastic materials with a stiffness coefficient of at least 1500 Mpa measured according to ISO 178 have been found to be usable. However, the shape stability of the forming element is determined not only by the material stiffness of the forming element but also by the shape of the forming element; the existence and location of corrugations in the forming element, especially, affect the shape stability.
A forming element in accordance with the invention can be formed of a plastic layer that is from approximately 0.2 mm to approximately 0.4 mm since it is provided with stiffening corrugations. Depending on the location and form of the corrugations, it can even, in certain cases, be possible to use plastic layers of a lesser thickness than 0.2 mm. In this context, the term corrugations denotes portions of a layer material which project out from the main plane of the material. The corrugations must be arranged in a direction that is parallel with the deformation forces that are to be counteracted by the corrugations. For example, transverse compression of an absorbent article is counteracted by arranging transverse corrugations, i.e. corrugations that extend in the transverse direction of the article.
Due to the fact that it is possible, according to the invention, to form a forming element of a thinner material whilst retaining high shape stability in the forming element, significant advantages of use are achieved regarding discretion and comfort. Corrugations are arranged in the forming element to create a greater rigidity and thereby shape stability within the portions of the forming element where high shape stability is critical to the fit and attachment of an absorbent article of which the forming element is a part.
An absorbent article of the type which is intended during use to essentially be accommodated in the crotch area of the user exhibits two end portions, intended to be directed backwards and forwards, respectively, on the user. Between the end portions there is an intermediate portion, which constitutes the transition between the two end portions and is narrower than these. The proportions between the various portions can vary somewhat between different articles, for example depending on the size of the article. However, the forward end portion is preferably approximately 1.5-5 times broader than the intermediate portion in order to prevent the article from shifting backwards on the user during use. The stiffening corrugations which, in accordance with the invention, are arranged in the forming element of the article, are principally arranged in the end portions of the article.
The corrugations in the forming element can be arranged only in the first or only in the second end portion. Alternatively, and preferably, the corrugations can be present in both end portions. In order to achieve a good effect with corrugations arranged only in one of the end portions, it can be suitable to form the forming element of a material with greater thickness in the end portion without corrugations. The thickness of the end portion without corrugations should then be greater than approximately 0.4 mm. However, such an embodiment is less preferable as it is more difficult to manufacture and gives the article a greater weight and reduced comfort.
The corrugations can be formed as elongate raised portions or depressions in the upper side of the forming element. The term the upper side of the forming element relates to that side of the forming element which, when it is arranged in an absorbent article, is intended to face towards the body of the user during use. The corrugations can also be formed as raised or depressed continuous areas with another suitable form. It has been shown that a plurality of separate corrugations arranged over a certain area on the forming element give a greater stiffening effect than arranging one continuous corrugation over a corresponding area.
Further, it can be advantageous to combine raised and depressed corrugations within the same area of the forming element.
The corrugations in the first end portion can be constituted of a raised or depressed area with a surface of approximately 5xc3x973 cm2xc2x15 cm2.
The corrugations can also be constituted of two or more elongate raised portions or depressions in the upper side of the forming element. These are arranged with their longitudinal direction principally in the transverse direction of the forming element. The corrugations can be separate or continuous in a curve, for example in an S-shape. The first end portion of the forming element is preferably formed with increasing width towards the short end of the forming element. The length of the corrugations follows the width of the end portion, i.e. they are longer the nearer they are located to the short side of the forming element. The elongate corrugations suitably have a height, or a depth, measured from the plane of the forming element that is from approximately 1.5 to 5 mm and a width that is from approximately 0.3 mm to 10 mm, preferably approximately 0.5 mm. The length can vary within fairly wide limits and can be from approximately 0.8 cm to 8 cm.
Furthermore, the corrugations do not require to have the same height along their entire length; the height can vary. For example, the corrugations can be higher at the outer edges of the forming element and lower therebetween, or vice versa.
The corrugations in the second end portion exhibiting the ridge-like raised portion can be constituted of a continuous raised area symmetrically arranged on either side of the ridge-like raised portion. The corrugations can also be formed as elongate raised portions with their longitudinal direction principally in the transverse direction of the forming element, i.e. extending across the ridge-like raised portion. The elongate corrugations in the second end portion can be, for example, 3-10 in number and can extend on one or both sides of the ridge-like raised portion. Such elongate corrugations suitably have a height or a depth that is approximately 1.5-5 mm, a width that is approximately 0.3-10 mm and a length that is approximately 0.8-20 mm.
By arranging corrugations which end a distance within the edge portions of the forming element, a deformation zone in the forming element is obtained nearest the edge. Such an embodiment can be advantageous from the point of view of comfort but can also be utilised to achieve a forming effect. For example, transverse corrugations arranged in the first portion of the forming element, i.e. that portion which is intended to be directed forwards on a user during use, can, in this way, be used to create an indication to form a cup-shape during use.
The length of the corrugations follows the contour of the forming element, i.e. a corrugation is longer in the wider part of the forming element and shorter in the narrower part.
Due to the fact that the intermediate portion is essentially free of corrugations, an article containing such a forming element can be formed flat and can then be given an anatomically correct form under the influence of the compressing forces to which the article is subjected during use. An article that is formed in this manner during use is described in SE 9702463-2.
By arranging the corrugations in the first end portion so that they follow the contour of the forming element and by making the corrugations end a distance within the side edge of the forming element, the forming element will be perfectly formed to a cup around the mons veneris of the user during use.
An absorbent article in accordance with the invention preferably exhibits a central longitudinal raised portion in that end portion which is intended to be directed backwards on a user during use. Such a raised portion can be wholly or partially formed by the forming element. Moreover, the raised portion can be wholly or partially constructed of other materials, for example absorbent materials. It is also possible to create raised portions that are not activated until the article is used, by means of folding indications in the forming element and/or the absorbent body of the absorbent article.